With DC isolated power supply: suitable for modifying speakers, power amplifiers, and car-mounted Bluetooth functions to solve common ground current noise and noise 2 mobile phones can be connected at the same time (: automatically return to the chain after powering on, and finally pair the mobile phone, the second one needs to be manually clicked in the mobile phone pairing list to connect) With call, CSRA64215 low power consumption, power on, the default volume is maximum Using the amp chip, the sound quality is better GND and : 3.7V lithium battery power supply (3.3V-4.2V) GND and VCC: select 5V or 12V power supply according to the DC isolation module L, G, R are single-ended outputs, which can be connected to input devices such as headphones, power amplifiers, and audio M+ and M- are the positive and negative poles of the microphone head is the common terminal of the button, the other end of the button is connected to +, -, PREV, , PLY respectively, and the length of the button line is within 5cm Key "+": short press to increase the volume, long press to continuously increase the volume "-": Short press to decrease the volume, long press to continuously decrease the volume "": short press the song "PREV": short press the previous song "PLY": short press to play/pause//hang up, long press for 1 second to reject incoming calls function "PLY": long press for 3 seconds to force into pairing mode, long press for 6 seconds to clear the pairing list "PLY"+"+": Press and hold for 1 second at the same time to enter the search TWS mode "PLY"+"-": Press and hold for 1 second at the same time to enter the searched TWS mode "+"+"-": Press and hold for 1 second at the same time to disconnect TWS Colour:green Material:PCB type:5V Package Contents: 1 x Bluetooth Receiver Board Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.